KR20000022000A - Hygienic paper produced by modifying coarse fiber and production method thereof - Google Patents

Abstract

PURPOSE: A method is provided to modify a coarse pulp of a high yield rate obtained from a source of recycled newsprint into a suitable pulp for producing a soft tissue-typed product. CONSTITUTION: A method for producing a hygienic paper contains steps of: generating a pulp slurry by pulping a coarse fiber in water during an agitation; decreasing a content of fines and increasing the water filtering degree of Canadian standard by using a washing liquid of pulp of valid amount; inducing a pulp into a head box of a paper-making machine in a paper-making concentration of 1.0%-0.01%; and producing a product of hygienic paper using the pulp in a paper-making process. The washing liquid of pulp of a valid amount is able to decrease the content of fineness under 35%, and increase the Canadian standard water filtering degree over 50. The hygienic paper product produced using the pulp is the 3.2-15.9kg/ream basic weight.

Description

Sanitary paper products produced by modifying coarse fibers and methods for making the same.

Typically in the paper industry, there is a general correlation between fiber coarseness and the softness or handfeel of the resulting paper product.

High quality fibers, such as bleached northern softwood kraft fibers, are fine and flexible and are used to make desirable soft tissue products. In contrast, mechanically pulping softwood produces high yield, coarse, stiff fibers, typically used to make newsprint.

In general, newspapers are mainly coarse, high yield fibers, typically stone groundwood (SGW), thermomechanical pulp (TMP), and / or chemical thermomechanical pulp (CTMP). Fiber. Such coarse newspaper fibers are usually considerably refined to cause crushing and fibrillation which help to give strength to the resulting newspaper paper. The refining results in a change in the degree of freedom of the coarse fiber from the fiber with the high freeness to the fiber with the low freeness. If the above high yields of coarse mechanically pulped tablet fibers are used in tissue products, the resulting sheets will not be soft and most would be undesirable as tissue products.

The relationship between tissue years and fiber roughness is thoroughly discussed in Canadian Patent No. 2,076,615. Attempts to produce soft tissue or towel type sanitary paper products from most high yield coarse fibers such as CTMP, TMP or SGW pulp have not been successful. Likewise, regeneration of old newspapers to produce soft tissue and towel products has been partly unsuccessful due to the low degree of freeness of the main fibers, the coarse, and the high levels of fines.

Other complex factors in the production of soft tissue and towel products from recycled newspapers are problems associated with paper machine operation due to poor drainage of low-fiber fibers and problems with particulates and other substances that accumulate in paper machine water systems (whitewater). . These materials make it difficult to creep tissue products from Yankee drying cylinders and operate the paper machine without achieving maximum years.

Soft paper products made from high yield coarse fibers, such as recycled newspapers, need to be felt and unmet for a long time. There is also a need for an economical and practical method of treating high yield coarse fibers from recycled newspapers to make them suitable for producing soft paper products. This need also extends to methods of processing newspapers or newspapers to be suitable for producing soft paper products and the treated fiber containing soft paper products.

Justice

As used herein, the term “comprise” refers to part (s) of the whole but does not exclude other parts. That is, the term “consist of” is an open word that requires that the stated component or structure or equivalent thereof is present but does not exclude the presence of other components or structures. The term "consist of" has the same meaning as the terms "comprise" and "have" and are interchangeable.

The term "machine direction" as used herein refers to the direction of movement of the forming surface on which fibers are deposited thereon during the formation of the material.

As used herein, the term “cross-machine direction” means a direction in the same plane perpendicular to the longitudinal direction.

As used herein, the term “cellulose” refers to a natural carbohydrate that is of formula (C ₅ H ₁₀ O ₅ ) _n and consists of anhydroglucose units bonded by an oxygen linker to form an essentially linear long molecular chain. High polymer (polysaccharide). Natural sources of cellulose include deciduous and coniferous trees, cotton, flax, African whiskers, milkweed, straw, jute, hemp, and bagasse.

As used herein, the term "roughness" is the weight per unit of length of fiber expressed in mg / 100m. Typically, fibers having a value of at least about 12 mg / 100 m are considered rough.

The present invention solves the problems of the prior art as described above, and seeks to obtain a method of reforming high yield coarse type pulp from a source such as recycled newspaper into a pulp suitable for producing soft tissue type products.

In accordance with the present invention, the coarse low-yield high yield type pulp found in newspaper (ie newspaper) can be modified to produce a soft tissue product by washing the pulp to reduce the proportion of particulate in the pulp.

The method of making a sanitary paper product from coarse fibers comprises (a) pulping coarse fibers in water while stirring to produce a pulp slurry, wherein the average granular content of the pulp prepared from coarse fibers is at least about 40%, (b) using an effective amount of pulp wash to reduce the powder content and increase the Canadian standard freeness, (c) introducing the pulp at a paper concentration into the paper box's headbox, and (d) the pulp in the papermaking process. Manufacturing a sanitary paper product using a.

An effective amount of pulp wash may reduce the granular content by less than about 35% and increase the Canadian standard freeness by about 50 or more. The pulp may be introduced into the paper machine at paper concentrations ranging from about 1.0% to about 0.01%.

The present invention includes the aforementioned process, wherein the sanitary paper product made using pulp is a tissue paper made from 3.2 to 15.9 kg / ream (7 to 35 pounds / lead) of basis weight. The sanitary paper product may also be a paper towel made from a basis weight of 5.4 to 18 kg / year (12 to 40 pounds / year). The sanitary paper product may also be a paper napkin made from a basis weight of 3.2 to 15.9 kg / lead (7 to 35 pounds / lead).

In general, pulp may be composed of cellulosic fibers, wherein at least 60% of the cellulosic fibers are coarse fibers having a Kajaani roughness of at least 12 mg / 100 m. For example, the pulp may be composed of recycled newspaper fibers in which at least 60% of the recycled newspaper fibers have a Kayani roughness of 17 mg / 100 m.

Pulp obtained from a source, such as recycled newspaper, may have an average powder content of at least about 40% prior to treatment. For example, the average granular content of the pulp may be at least about 46% before treatment. As another example, the average granular content of the pulp may be greater than about 48% prior to treatment.

The Canadian standard freeness of pulp obtained from sources such as recycled newspaper may be less than about 300 prior to treatment. For example, the pulp may have a Canadian standard freeness of less than about 270 prior to treatment. As another example, the pulp may have a Canadian standard freeness of less than about 200 prior to treatment.

According to the present invention, the pulp obtained from a source such as recycled newspaper is washed to reduce the powder content to less than about 35%. For example, the pulp is washed to reduce the powder content to less than about 30%. As another example, the pulp is washed to reduce the powder content to less than about 29%.

In one aspect of the invention, pulp obtained from a source, such as recycled newspaper, is washed to increase the Canadian standard freeness by at least about 50. For example, the pulp is washed to increase the Canadian standard free water by about 70 or more. As another example, the pulp is washed to increase the Canadian standard degrees of freedom by at least about 90 degrees.

The invention also includes a method of modifying pulp obtained from recycled newspapers to improve tissue and towel making properties. The method of reforming pulp obtained from recycled newspapers includes the steps of (a) pulping newspaper paper in water with stirring to produce a pulp slurry, wherein the pulp obtained from newspapers has an average granular content of about 40% or more, (b) an effective amount of Using a pulp wash to reduce the powder content and increasing the Canadian standard freeness, and (c) introducing the pulp at a paper concentration into the paper box's headbox to use the pulp in the papermaking process to produce sanitary paper products. Steps.

An effective amount of pulp wash can reduce the powder content to less than about 35% and increase the Canadian standard freeness by about 50 or more. The pulp may be introduced into the papermaking machine at a papermaking concentration ranging from about 1.0% to about 0.01%.

One embodiment of the present invention comprises the steps of (a) pulping newspaper paper in water with stirring to produce a pulp slurry, and (b) a pulp having a powder content of pulp of less than about 35% and a Canadian standard freeness of about 300 or more. A method of modifying pulp obtained from recycled newspapers, the method comprising the step of introducing into the paper machine headbox at a paper concentration to produce a sanitary paper product for use in the papermaking process.

Another embodiment of the present invention includes a sanitary paper product having fibers modified from coarse fibers. The product has a reduced particulate content of less than about 40% and a standard Canadian degree of freedom up to about 250 or more.

In general, the present invention provides a method for treating high yield of coarse fiber pulp obtained from recycled newspaper paper containing a relatively high level of fines and having a relatively low Canadian standard freeness. According to the present invention, the relatively low quality pulp can be treated and used to produce soft paper products.

The present invention is based on the discovery that modifying recycled newspaper pulp can produce a very soft tissue-like product with a product quality comparable to tissue products made from expensive bleached northern softwood kraft fibers. Generally, recycled newspaper pulp consists of coarse high yield form fibers (ie, fibers produced primarily by mechanical separation of wood fibers and typically comprising at least 60% by weight of source material). These cellulosic fibers include high roughness fibers having a roughness of at least 120 mg / 100 m. Recycled newspaper pulp typically contains powder at levels of about 40% or greater and has a CSF of less than about 300. If low-quality pulp is treated using an effective amount of pulp wash to lower the granular content to less than about 35% and increase the CSF by about 50 or more, soft tissue-like products can be made using such low-quality pulp.

In general, coarse fibers from sources such as recycled newspapers are pulped using conventional techniques. However, certain deking and / or fiber cleaning or manufacturing techniques are contemplated.

For example, recycled newspapers may be slurried at a concentration of about 3% to 18% at a temperature of about 37.8 ° C. to 82.2 ° C. (100 ° F. to 180 ° F.). After slurrying, the pH of the pulp slurry can be adjusted and the temperature reduced to a temperature and pH suitable to open and swell the fibers. The pH of the pulp slurry may be less than about 8 (although alkaline conditions may be used). Preferably, the pH may be about 4-7 and temperatures of less than about 65.6 ° C. (150 ° F.), preferably at least about 37.8 ° C. (100 ° F.), may be used.

After pulping the slurry, the slurry is dewatered to a concentration of about 15% to about 35%. One instrument for carrying out the “dehydration” process described herein in connection with the present invention may be purchased from Voice-Sulzer Paper Technology, Appleton, Wisconsin.

After dewatering the pulp, it can be crumbled to control the size of the broken fibers. In general, crumb is not usually necessary for recycled newspaper pulp. One instrument that performs the “crumbing” process described herein in connection with the present invention may be purchased from a Scott equipment company in New Prag, Minn. Other suitable devices will be apparent to those skilled in the art.

Starting with the used newspaper, the method of the present invention is broadly carried out by (1) slurrying newspaper paper in water with stirring to pulp the newspaper paper, (2) washing the pulp to remove particulates and increasing the degree of freedom, And (3) using the slurried pulp as part of the furnish in the sanitary paper making process, preferably in the papermaking process.

At several concentrations, starting with slurrying newspaper or old newspaper at a concentration of about 3-18%, preferably at a temperature of pulp slurry of at least about 37.8 ° C. (100 ° F.) and maintaining it at elevated temperature for at least about 15 minutes Slurrying is carried out. Thereafter, the temperature of the pulp slurry is reduced. Preferably the pulp is maintained at a pH of 4-7 and at elevated temperatures of about 60 ° C. (140 ° F.) or less, preferably about 37.8 ° C. (100 ° F.) or more.

Preferably, the pulping process comprises pulping old newspaper at a concentration of 6-9% and elevated temperatures of about 37.8 ° C.-82 ° C. (100 ° F.-180 ° F.). Pulping times can range from 15 to 60 minutes. The slurry can then be cooled to 37.8 ° C.-65.6 ° C. (100 ° F.-150 ° F.), transferred to a holding chest / blend chest, and the pH adjusted to 4-7 and preferably fixed for about 30 minutes.

The pulp is then washed to remove particulates and increase the degree of freedom. Conventional washing techniques can be used until a sufficient amount of powder is removed and an increase in the degree of freedom is achieved.

After the washing step, the pulp is prepared for the papermaking process. No additional screening is necessary, although screening and / or centrifugal cleaning can be performed to remove large contaminants such as paper clips to protect the paper machine. If desired, the free floats and dissolved materials may be washed off the paper machine forming fabric and removed from the paper machine whitewater using a floating step for contaminant removal of the paper machine whitewater. Dissolved air flotation processes, such as sidehill screens and crofter purifiers, may be used to clean the whitewater for use in paper machines.

Although the present invention is not intended to be bound by a particular theory of operation, cleaning may result in cleaning of softer paper products by washing away and removing particulates and other components (eg, small particulates) of the pulp that tend to reduce the freeness of the pulp sample. It is believed to help produce.

Years are difficult to measure or quantify for tissue products because they are typically perceived by the touch, which is affected by smoothness and other surface properties in addition to sheet puffiness. Tactile tests have been developed and the tactile data reported herein are generally obtained according to the following tests.

Tactile test

range

Several different lightweight dry crepe tissues for use as a standard were purchased or made from commercial pulp of different qualities to give the tissue product a year. These tissues were used to define numerical year scales. Numeric values are assigned to the year of each tissue standard.

The touch of the softest product made from commercially available pulp was assigned to 86, a lightweight dry crepe tissue produced from 50% Irving Northern Softwood Kraft Fiber and Santa Fe Eucalyptus Kraft Pulp. The roughest product for the standard was made from 100% bleached softwood chemical thermomechanical pulp (SWCTMP), assigned a touch of 20 on the scale. Another lightweight dry crepe tissue sample for defining a “tactile year” scale and for use as a standard with a year value between the softest and roughest standards was made from different pulp or pulp blends and assigned a tactile year value between 20 and 86 It was. The pulp used is further described in the following paragraphs. In addition to the lightweight dry crepe method, pulp fibers other than those used to make tissue manufacturing methods and standards can produce tissue products outside of the 20 to 86 tactile flue scale defined by the tissue standards described herein. However, for the purpose of improving the years achievable using the present invention, the tactile year range defined above for lightweight, dry crepe products, between 20 and 86, is accurate and sufficient for comparison purposes. The recycled newsprint fibers of the present invention could produce tissue products having a age value of 86 or greater when used in other tissue making processes, such as through drying processes or when blended with other fibers.

Pulp used to make tactile standards

(a) Bleached softwood chemical thermomechanical pulp (SWCTMP) (Temcel Grade 500/80) with a Canadian Standard Yeosu (CSF) of 500 and an ISO brightness of 80 was prepared from black spruce and balsam fir. After pulping with sodium sulfite pretreatment and purifying under pressure, it was bleached with alkali peroxide up to 80 ° ISO brightness. The kayani roughness of the fiber was the same as 27.8mg / 100m and the kayani weight average fiber length was 1.7mm.

(b) Bleached Northern Softwood Kraft (NSWK) (Pictow Grade 100 / 0-100% Softwood) was prepared from Black Spruce and Balsam Fir. Kappa # = after the pulp by the kraft method was bleached to 26 DEO CE _o to 88 ° ISO brightness. Kayani roughness was equal to 14.3 mg / 100 m, and the Kayani weight average fiber length was 2.2 mm.

(c) Bleached recycled fiber (RF) was prepared from assorted mixed office waste that was pulped, screened, washed and washed to 550 ° C.F, and bleached with sodium hypochlorite to 88 ° ISO brightness. Kayani roughness was equal to 12.2 mg / 100 m and the Kayani weight average fiber length was 7.2 mm.

(d) Bleached eucalyptus kraft pulp (BEK) (Santa Fe elemental chlorine glass grade) was pulped by Kraft method up to Kappa # = 12 and eucalyptus globule by ODE _o D bleaching to 89 ° ISO brightness. From Eucalyptus Globulus. The Kayani roughness was equal to 6.8 mg / 100 m and the Kayani weight average fiber length was 0.85 mm.

(e) Bleached Southern Softwood Kraft (SSWK) (Scottmobile Pine) was made of Loblolly and Slash pine, pulped to Kappa # 26 and CEHED bleached to 86 ° ISO brightness. The Kayani roughness was equal to 27.8 mg / 100 m and the Kayani weight average fiber length was 2.6 mm.

(f) Bleached hardwood chemical thermomechanical pulp (HWCTMP) (Miller Western Grade 450/83/100) with a Canadian Standard Freedom Water (CSF) of 450 and an ISO brightness of 83 was prepared from the aspen. It was pulped by alkali peroxide pretreatment, purified under pressure and bleached with alkali peroxide. The kayani roughness of the fiber was equal to 13.8 mg / 100 m, and the kayani weight average fiber length was 0.85 mm.

Device

The test method does not require equipment. The test method uses the procedures and materials described below to evaluate tissue samples using 10 or more panels and classify the sample years on the year scale using product standards of known year scale values. Some samples were tested by a recognized tester using product standards of known year scale values. When used in place of test panels, the results of certified testers were identical.

Sample manufacture

1. Five samples to be tested shall be selected by the evaluator panel.

2. Calculate the required number of sample pads and standard number of pads for the judge's test panel for each product to be evaluated for the year using the following formula:

Required Pads (each product) = (x-1) x (y)

Where x = number of products to be tested and y = number of people in the test panel

3. Randomly select a roll of sample tissue for each product to be evaluated and discard the first few sheets (to remove the tail tying glue).

Test pads are prepared from each roll of product to be tested. Each pad should be 4 sheets thick and made from a continuous sample of 4 sheet long tissue. Each pad is prepared as follows: The four sheet length sample is first folded in half. This results in a sample with a thickness twice as long as two sheets. The double thickness sample is then folded back in half to make a 4 sheet thick, 1 sheet length sample pad. When on the roll of tissue, the outer surface of the sheet should be folded to be the outer surface of the pad. If the product to be tested is "duplex", i.e. has different surface properties on the outer surface of the sheet compared to the surface facing the inside of the roll, once tested on the surface facing the outside of the roll as the outer surface of the sample pad It should also be tested on a separate sample pad made with the sheet surface folded and facing the inside of the roll being the outer surface of the sample pad.

4. Use the formula in item 2 above to find the number of pads required for each product. If more than one roll of product is needed to produce the required number of pads, then it is important to randomize the pad pile with the product obtained from each roll. Code each pad with a batch code in the upper left hand corner (above the fold).

5. Select three standards from the standard tissues for reference by the panel as follows:

The roughest sample to be evaluated is selected and compared to a standard tissue sample pad, and a lower value standard that is slightly rougher than the roughest sample is selected.

Choose the softest product sample to evaluate and choose a standard tissue pad that is slightly higher (softer) than the softest sample to evaluate.

Select a third standard that falls approximately in the middle of the selected lower and higher standards.

The three selected standard tissue pads are tactile reference to the pad and define the softest, roughest and midrange.

6. Tactile references define the limits of the year range of the product to be evaluated by the panel. To be more accurate, the highest and lowest reference selected should be approximately 30 points away on the tactile year scale. The intermediate reference should be at least 8 points away from the lower and higher reference.

Panel member selection and instructions

1. Choose approximately 10 panels with approximately the same male and female ages of varying ages.

2. Keep the panel members on the instructions, and “enforce” them if necessary.

3. The panel must work in a quiet place.

Examination process

1. Read the following standard instructions and begin the year test.

Standard Instruction

Before beginning the year panel testing process, each panelist should read the following instructions.

a. purpose

"The purpose of this course is to compare the year of toilet tissue samples."

b. Way

"I'll give you two sample pads for toilet tissue at the same time. Compare each other with your hand and compare each sample with your hand." You can hit, bend or bite the sample if you think it's appropriate for your judgment. "

c. First decision

"After feeling each of the two sample pad pairs, you have to decide on a smoother sample."

d. Second decision

"Use the following ratings to grade the degree of difference in years between the two pads:

The scale uses odd 1, 3, 5, 7, 9. If you feel that the numbers listed below do not sufficiently represent the difference between the two products, you can use even numbers. "

Panel rating scale

The number on the rating scale is defined as follows:

1. No difference.

3. The difference is so small that you cannot be confident that some people may miss it.

5. Small differences confident in judging.

7. Moderate differences that can be recognized easily and confidently.

9. A very big difference that can be easily recognized and remembered.

e. Graduation

"Before we start, I will give you the sample pads of the softest standard sample and the softest (roughest standard) product you want to use as a control. Please handle both. See two standards. You can rate the difference in the year you feel between dragons as 9 on the justice rating. " (9 on the rating scale is equivalent to the number of tactile points on the year scale between the higher and lower reference references selected for the panel in step 5.)

f. Participant Response

"What questions do you have about the exam process?"

g. reconfirm

"Finally, don't worry too much about each decision. Your opinion is the same as the opinion of others. There is no right or wrong answer!"

2. Give each panel member a combination of reference pads and sample pads to let them select the desired sample and then grade the difference using a year on a scale of 1-9. Each panelist should receive a pair in random order to avoid a series of errors.

3. Record the results of each pair as XY _n . When X is the preferred sample code, Y is the undesirable sample code and n is the scale value (1 to 9).

Data analysis

If the paired comparison results in a scale ratio, it is processed. The definition of the scale ratio is given as follows: If the scale does not change under the positive linear transformation form y = x, a> 0, this scale is the scale ratio.

The data pairs and weight ratios for the "n" number of pads are placed in a rectangular matrix of the form

In the above, O _i is each sample and W _i is a scale value (weight ratio) for each pair.

In the case of the rectangular matrix of this type, the following properties exist.

AW = MW

In the above, W = (W ₁ , W ₂ , ... W _n ). The weight vector W is the eigenvector of the matrix A corresponding to the eigenvalue n. Saaty has shown that it is necessary to know the largest eigenvalue (λ max) of A in order to derive the eigenvector W from the estimated weight [Saaty, TL, “A Scaling Method for Priorities in Hierarchical Structures. ", Journal of Mathematical Psychology, 15, 234-281 (1977) and Saaty, TL," Measuring the Fuzziness of Sets ", Journal of Cybernetics, 4 (4), 53-61 (1974)). Computer programs for obtaining λ max and W are described in McConnell, Wes, "Product Development Using Fuzzy Sets", INDA Tenth Technical Symposium, pp. 55-72, November 17-19, 1982]. The eigenvector W obtained is the best evaluation scale ratio of the paired input values. Taking the logarithm of each component in the vector creates a more familiar equidistant scale, where the distance between objects is a straight line. The standard year values are plotted against the evaluated equally scaled values and assigned numerical values by interpolation for unknown samples.

The average and standard deviation of the standard year values of each unknown sample are calculated from the standard year values calculated for all panel members. If the value of any individual panel member falls outside of 2 standard deviations from the mean, the value is discarded and the mean and standard deviation are recalculated. The mean of a standard year value without a value outside of 2 standard deviations from the mean is the standard tactile year value for an unknown sample.

Tactile year scale

The tensile strength

Tensile strength values provided for tissue-like paper products herein are measured by cut length test using 5.08 cm sample span and 5.08 cm / min cross head speed (TAPPI Test Method No. T494om-88). Typically, tissue strength differs in the longitudinal versus transverse direction of the sheet. In addition, the basis weight of the tissue sample, which affects the tensile strength, changes. In order to better compare tensile strength from various tissue samples, it is important to correct for differences in the basis weight of the samples and longitudinal differences in the tensile strength. This can be corrected by calculating “standardized tensile strength (hereinafter“ standardized tensile strength ”or“ NTS) ”as the basis weight and directivity.) The NTS is calculated as the square root of the longitudinal and transverse tensile strength of the product. The calculated tensile strength standard for the difference in basis weight and longitudinal direction is designed to better compare tissue samples, and measures the tensile strength in the longitudinal and transverse directions, and the TAPPI test method number. Determine the basis weight for the tissue sample according to T410om-88. When using British units for the measurements, the tensile strength is measured in ounces per inch and the basis weight is measured in pounds per year (2880 feet ² ). calculating a tensile strength in g / 2.54cm, the basis weight is measured in g / m ^2. is set to the test device is to cut a sample in inches used to test the tensile It should be noted that the metric unit is not pure metric because the unit of measurement results in g / 2.54 cm, the abbreviation MDT for longitudinal tension, CDT for lateral tension and BW for basis weight, And the mathematical formula of the standardized tensile strength (NTS) of directivity is as follows:

NTS = (MDT x CDT) ^1/2 / BW

NTS (UK) = 0.060 x NTS (metric units defined above)

Powder

The level of granulation in the pulp sample is based on the measurement of fiber length or particle length. "Average fiber length" refers to the weighted average length of pulp fibers measured using a Kajaani Fiber Analyzer Model No. FS-100 from Kajaani Cucumber Electronics, Kajaani, Finland. Depending on the test procedure, the pulp sample is treated with cold dip to ensure that no fiber bundles or sheaves are present. Each pulp sample is digested in hot water and diluted to approximately 0.001% solution. Individual test samples are withdrawn from the dilution solution in about 50-100 ml portions when tested using the standard Kajaani fiber analysis test procedure. The weighted average fiber length can be represented by the following formula:

∑ (X _i * n _i ) / n

x _i = 0

Where k is the maximum fiber length,

x _i is fiber length,

n _i is the number of fibers having length x _i ,

n is the total number of fibers measured.

"Low average fiber length pulp" means pulp and by-products of the papermaking process containing significant amounts of short and non-fiber particles. In many cases, these materials can be difficult to form paper sheets, making relatively dense and impermeable paper sheets or nonwoven webs. The low average fiber length pulp is, for example, an average fiber length of less than about 1.2 mm, as measured by an optical fiber analyzer such as Kayani Fiber Analyzer Model No. FS-100 (manufactured by Kayani Oil Electronics, Kaani, Finland). It can have For example, low average fiber length pulp can have an average fiber length of about 0.6 to 1.2 mm. In general, most fibrous or cellulosic components of papermaking sludge can be considered low average fiber length pulp (short and non-fiber particles). In many cases, the fibrous or cellulose component is not less than 40% "powdered," as measured by an optical fiber analyzer such as, for example, Kayani Fiber Analyzer Model No. FS-100 (manufactured by Kayani Oil Electronics, Kaani, Finland). Low average fiber length pulp containing "(ie, particles similar to fibers up to about 0.2 mm in length).

Yeosu-do

Freedom is a measure of the rate at which a thin pulp suspension can drain. The degree of freedom was measured using a Canadian standard freeness tester according to TAOOI T 227 m-28 and CPPA Standard C.1 (1952), using the procedure for groundwood pulp samples. The Canadian Standard Yeosu Tester is a testing machine, Inc., Amityville, NY.

Tissue Making Method

The washed pulp obtained from recycled newspaper produced by the process of the present invention can be used in any commonly known papermaking process for producing soft bulky sanitary paper webs such as tissues, towels, napkins and facial tissues. have. Many different papermaking methods are suitable, including those in which the web is dried through can drying, through drying, thermal drying and combinations thereof.

Representative types of papermaking methods that should be used in connection with the present invention are described in US Pat. No. 3,301,746 to Sanford et al .; No. 3,821,068 to Shaw et al .; No. 3,812,000 to Salvucci et al .; Morgan, Jr. et al. 3,994,771; 4,102, 737 to Morton; 4,158,594 to Becker et al .; 4,440,597 to Wells et al .; And the methods taught in US Pat. No. 5,048,589 to Cook et al.

Preferred papermaking methods are commonly known as dry creep methods. Generally, the method includes the step of using the paper furnish of the invention where dry strength chemicals are preferably added to produce tensile strength and other papermaking chemicals can be added. The paper furnish is then pumped from the machine chest, flowed into the headbox, and the surfactant system added. The paper furnish then flows through the slices at a concentration of 0.1-0.4% onto the horizontal surface of the Fourdrinier wire through which water is removed and a web is formed. The wire cloth is entrained around the breast roll and several table rolls, then intrained to the wire turning rolls, then fed from the wide turning rolls around the couch rolls and several guide rolls and into the breast rolls. Go back. One of the rolls is driven to propel the forward linear wires. One or more vacuum boxes (deflector or hydrofoil) may be used between the table rolls to enhance water removal.

A wet web is formed on the top surface of the forewood linear, which is squeezed onto the felt with a coach roll or transferred to the felt by transferring the sheet to the felt with a pick-up shoe. The felt carries the web up to the press assembly. The felt is then moved around one or two press rolls, one of which may be a suction roll, then intrained around the guide rolls and circulated back to the couch rolls. Shower heads and guard boards can be used at various locations on the felt surface to assist in web pick up, cleaning and conditioning of the felt surface. The press assembly may comprise a single press roll or a top and bottom press roll. Moisture is removed from the nip of the press assembly and transferred into the felt.

The formed and compressed web is transferred to the surface of a rotary drying cylinder, referred to as Yankee drying. The drying assembly may also include a hot air hood surrounding the top end of the Yankee cylinder. The hood has a hot air nozzle that hits the web to assist in the removal of moisture. The hood includes exhaust gases to control the temperature by removing air from the hood chamber. The doctor blade is used to remove the web from the dry surface to impart crepe to the web. To help remove the web from the dry surface in a controlled and uniform condition, a creping adhesive is applied to the Yankee surface using a spray system. The spray system is a series of spray nozzles attached to header pipes that extend across the width of the dryer surface. The creping adhesive may be of any type commonly used in tissue paper making techniques.

The creped paper web from the dry cylinder is passed through a nip formed by a pair of rolls and wound into a large roll called a parent roll. The tissue paper making method used in the examples can generally be characterized as a lightweight dry crepe method. The 14 inch wide pilot plant scale machine was operated as follows.

The paper furnish is incorporated into the machine chest prior to web formation, followed by incorporation of dry strength adhesives, dyes or other chemical additives. A paper furnish is passed through the fan pump through the slice from the headbox at a concentration of 0.1% to 0.4%, which flows onto the horizontal surface of the forelinear wire where water is removed and web formation occurs as it passes. The wire is intrained around the suction breast roll and assists in water removal and web formation. The wire is intrained around several guide rolls and wire turning rolls and fed back to the breast rolls. One of these rolls is driven to propel the forward linear wire.

A wet web is formed on the top surface of the forelinear and transferred to the felt by vacuum pickup. The felt carries the sheet to the press roll assembly. The felt is moved around one press roll, a solid rubber roll, intrain around the guide roll and circulated back to the vacuum pickup. Moisture is removed from the nip of the press-roll and transferred to the felt.

The formed web is compacted and transferred to the surface of a rotary drying cylinder, commonly referred to as a Yankee dryer. The doctor blade is used to remove the web from the surface of the Yankee in wet dry between 95% and 96%. To help remove the web from the dryer surface in a controlled uniform condition, a creping adhesive is applied to the Yankee surface using a spray nozzle. The adhesive mixture used in these examples was a 70/30 mixture of 70% polyvinyl alcohol and 30% latex based starch (National Starch Latex 4441).

The paper web creped from the drying cylinder was wound through a nip formed by a pair of rolls and into a parent roll of the desired size for testing. The paper machine formed a 14 inch wide web and was operated at a reel speed of 12.2-15.2 m / min (40-50 ft / min). All dry crepe tissue samples of the examples were produced with a basis weight of 3.6 kg / lead (8 pounds / lead) and 18-20% crepes. Samples were changed to 2-ply tissue (7.3 kg / year (16 pounds / year)) for all tests.

The invention is illustrated in the following examples. All ratios used herein are by weight unless otherwise indicated, and fiber weights are based on the weight of air dried fibers unless otherwise indicated.

<Example 1>

Dry lightweight crepe tissue products were made from pulp obtained by pulping old newspapers. Control and sample tissues were prepared. The tissue product was made by pulping with water for 20 minutes at 6% concentration, 150 ° F. and pH about 7. The pulp slurry was held at 130 ° F. for 30 minutes and then split in half.

The first portion of the pulp slurry was purified using a batch purifier at a rate of 1 horsepower / ton, and then directly used as a furnish for lightweight dry crepe tissue using the method and papermaking equipment described above, with a basis weight of 7.3 kg. Two-ply tissue was made with / lead (ie 3.6 kg / lead / ply) (16 lbs / lead (ie 8 lbs / lead / ply)).

The remaining portion of the pulp slurry was adjusted to 3% slurry concentration and washed to 5% target concentration. This washing step reduced the concentration of fines in the pulp and increased the freeness as measured by the Canadian standard freeness test.

The pulp was purified at a rate of 1 horsepower / ton using a batch purifier and introduced into the paper machine at a paper concentration of approximately 0.1%. Subsequently, the basis weight was 7.3 kg / lead (ie 3.6 kg / lead / ply) (16 lbs / lead (ie 8 lbs / lead / ply)).

Control and sample dry crepe tissues were subjected to tactile and tension tests. The tactile test was performed basically as described above, except that one approved tester and a commercially available reference sample were used in place of the reference panel obtained from the test panel and the specific pulp. Four sets of samples were prepared and the number reported in the tactile results represents the mean value of four samples. The results were not analyzed using the weight ratio data analysis procedure described above. Test results are reported in Table 1.

Fiber roughness CSF before cleaning % Of granules before washing CSF after washing Granularity after washing (%) NTS (metric) 22.3 mg / m 230 43.6 360 32.0 8.0 30.8 mg / m 150 48.0 378 28.0 8.5

As indicated in Table 1, washing increased the CSF of the sample by more than 100, and the fractionation rate in one sample was reduced by less than 35% and in the other by less than 30%.

<Example 2>

Except for the addition of the dry strength agent, the sample from Example 2 was prepared substantially according to Example 1. Samples A and B were also prepared by circulating the water stream back into the pulp. Thus, most of the powder remained in the pulp. Samples C and D were prepared by washing the pulp and removing the granules.

The standardized tensile strength and feel of these samples are compared in Table 2 below. Each data point in Table 2 represents the average value of three samples.

sample NTS (metric) touch A 10.23 74 B 10.08 74 C 10.21 84 D 12.30 74

As indicated by the data in Table 2, the removal of the granules results in a paper with a greater tactile feel and approximately the same tensile strength (Sample C vs. Samples A and B) or a paper with approximately the same tactile but greater tensile strength (Sample D). Versus samples A and B).

Although the present invention has been described in connection with specific embodiments, it should be understood that the main details contained by the methods of the invention are not limited by the specific embodiments described above. On the contrary, the main subject matter of the present invention is intended to include all options, modifications, and equivalents which may be included within the spirit and scope of the following claims.

As described above, the high yield coarse type pulp obtained from a source such as recycled newspaper can be modified according to the method of the present invention to obtain a soft tissue type product.

Claims (18)

Pulping the coarse fibers in water with stirring to produce a pulp slurry, wherein the average granular content of the pulp obtained from the coarse fibers is at least about 40%, Using an effective amount of pulp wash to reduce the powder content and increase the Canadian standard freeness, Introducing pulp at a papermaking concentration into the paper box's headbox, and Manufacturing of sanitary paper products using pulp in the papermaking process Sanitary paper product manufacturing method from the coarse fiber comprising a. The method of claim 1 wherein the powder content is reduced by less than about 35% and the Canadian standard freeness is increased by at least about 50%. The method of claim 1 wherein the pulp is at a papermaking concentration ranging from about 1.0% to about 0.01%. The method of claim 1 wherein the pulp contains at least 60% of the cellulosic fibers having cellulosic fibers having a Kajaani roughness of 12 mg / 100 m. The method of claim 1, wherein the average granular content of the pulp obtained from the coarse fiber is at least about 45% before treatment. The method of claim 1 wherein the pulp obtained from the coarse fibers is washed to reduce the powder content to less than about 30%. The method of claim 1, wherein the pulp obtained from the coarse fibers is washed to increase the Canadian standard degree of freedom up to about 70 or more. The method of claim 1 wherein the sanitary paper product is a tissue paper made from a basis weight of 3.2 to 15.9 kg / lead (7 to 35 pounds / lead). The method of claim 1 wherein the sanitary paper product is a paper napkin made from a basis weight of 3.2 to 15.9 kg / lead (7 to 35 pounds / lead). The method of claim 1 wherein the sanitary paper product is a paper towel made from 5.4 to 18 kg / year (12 to 40 pounds / year). Pulping newspaper paper in water with stirring to produce a pulp slurry, wherein the average granular content of the pulp obtained from newspaper was at least about 40%, Using an effective amount of pulp wash to reduce the particle content and increase the Canadian standard freeness, and Introducing pulp at paper concentration into the paperbox headbox, where the pulp can be used in the papermaking process to make a sanitary paper product Method for reforming pulp obtained from recycled newspaper comprising a. The method of claim 11, wherein the segregation content is reduced by less than about 35% and the Canadian standard freeness is increased by about 50 or more. The method of claim 11 wherein the pulp is at a papermaking concentration ranging from about 1.0% to about 0.01%. The method according to claim 11, wherein the pulp contains cellulosic fibers wherein at least 60% are coarse fibers having at least 12 mg / 100 m of kayani roughness. The method of claim 11, wherein the average granular content of pulp obtained from newspaper is at least about 45% prior to treatment. The method of claim 11, wherein the pulp obtained from the newspaper is washed to reduce the powder content to less than about 30%. Pulping newspaper paper in water while stirring to produce a pulp slurry, and Introducing pulp with a powder content of less than about 35% and a Canadian standard freeness of about 300 or more into the papermaking concentration into the paper box, where the pulp can be used in the papermaking process to make sanitary paper products Method for reforming pulp obtained from recycled newspaper comprising a. A sanitary paper product containing fibers modified from coarse fibers with a reduced particulate content of less than about 40% and an increase in Canadian standard freeness up to about 250 or more.